title: Molecular epidemiology of extended-spectrum beta-lactamase-producing Escherichia coli in Tunisia and characterization of their virulence factors and plasmid addiction systems.
abstract: BACKGROUND
  Extended-spectrum β-lactamases (ESBLs), particularly CTX-M- type ESBLs, are among the most important resistance determinants spreading worldwide in Enterobacteriaceae. The aim of this study was to characterize a collection of 163 ESBL-producing Escherichia coli collected in Tunisia, their ESBL-encoding plasmids and plasmid associated addiction systems.
  
  
  RESULTS
  The collection comprised 163 ESBL producers collected from two university hospitals of Sfax between 1989 and 2009. 118 isolates harbored blaCTX-M gene (101 blaCTX-M-15 gene and 17 blaCTX-M-14 gene). 49 isolates carried blaSHV-12 gene, 9 blaSHV-2a gene and only 3 blaTEM-26 gene. 16 isolates produced both CTX-M and SHV-12. The 101 CTX-M-15-producing isolates were significantly associated to phylogroup B2 and exhibiting a high number of virulence factors. 24 (23.7%) of the group B2 isolates belonged to clonal complex ST131. Pulsed-field gel electrophoresis (PFGE) typing revealed a genetic diversity of the isolates. 144 ESBL determinants were transferable mostly by conjugation. The majority of plasmid carrying blaCTX-M-15 genes (72/88) were assigned to various single replicon or multireplicon IncF types and had significantly a higher frequency of addiction systems, notably the VagCD module.
  
  
  CONCLUSIONS
  This study demonstrates that the dissemination of CTX-M-15 producing E. coli in our setting was due to the spread of various IncF-type plasmids harboring multiple addiction systems, into related clones with high frequency of virulence determinants.
authors.affiliation: Laboratoire de Microbiologie, Hôpital Habib Bourguiba, Sfax, Tunisie. basma_mnif@yahoo.fr
authors.forename: Basma
authors.initials: B
authors.lastname: Mnif
authors.forename: Hela
authors.initials: H
authors.lastname: Harhour
authors.forename: Jihène
authors.initials: J
authors.lastname: Jdidi
authors.forename: Faouzia
authors.initials: F
authors.lastname: Mahjoubi
authors.forename: Nathalie
authors.initials: N
authors.lastname: Genel
authors.forename: Guillaume
authors.initials: G
authors.lastname: Arlet
authors.forename: Adnene
authors.initials: A
authors.lastname: Hammami
mesh_terms: D016000:Cluster Analysis; D003227:Conjugation, Genetic; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology; D022761:Gene Transfer, Horizontal; D006785:Hospitals, University; D006801:Humans; D017720:Molecular Epidemiology; D058889:Molecular Typing; D010957:Plasmids / Q000032:analysis* / Q000145:classification; D014416:Tunisia / Q000453:epidemiology; D037521:Virulence Factors / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D037521:Virulence Factors; D001618:beta-Lactamases